Mitral Valve Regurgitation in two Thoroughbred Stallions

Mitral valve (MV) disease is the most important valvular condition affecting athletic performance in horses. Twenty and 22 years old Thoroughbred Stallions used for breeding had suffered from increased respiratory and heart rate, poor performance and incomplete ejaculate release during covering, since three months ago. Cardiac examination projected irregular cardiac rhythm after a halt and an early-mid-systolic murmur.

Mitral regurgitation (MR) and valvular changes were visible on echocardiography. Also volume overload of the Left Atrium (LA) and Left Ventricle (LV) were observed. Color Flow Doppler echocardiography confirmed moderate mitral valve regurgitation. A band-like fibrous and nodular degeneration of the left coronary leaflet was present. There was minimal secondary left ventricular remodeling of the apex of the left ventricle due to chronic volume overload.

The therapeutic attempts included Quinapril and Furosemide. In these cases, normally no structural effect could be achieved, but clinical improvement and successful covering sessions were obtained, and when the therapy was terminated, clinical problems reappeared. In conclusion, in horses with MR, early diagnosis and appropriate therapy with Quinapril promises a reasonable performance.